Green’s Dictionary of Slang

(Irish) confusion, worry; thus the times of Molly Bán, a riotous good time.

1916		W. Ryan Letter in Share Slanguage n.p.: They were drawing a cordon round the city [...] This caused ‘Molly Bawn’ with us – we were trying to finish off the [whiskey] stills and shut down [BS].
1992		B. Leyden Departures n.p.: Why should they get married when Mammy does it all? They have the times of Molly Bán, with mothers dancing attendance on them [BS].